Title: The framework specification should also enable the usage of xml:id 

Description: 

The WS-Policy Framework specification uses wsu:id element to designate identification for elements[WS-Policy]. W3C also published xml:id document that allows the same use [XMLID] that is a recommendation. Currently, the WS-Policy specification does not use the xml:id mechanism for uniquely identifying XML elements and relies on the WSS definition of id mechanism. 

Justification: 

The purpose of the xml:id specification is to have unique element identifiers to be recognized by all conformant XML processors. Currently, WS-Policy relies on WS-Security specification for generating URI references instead and requires the framework providers to recognize this alternate mechanism for processing references. As xml:id will be adopted, the support of xml:id in all XML processors may require WS-Policy to also allow utilization of xml:id. Further, the specification does not clarify whether the xml:id is permissable as an identification mechanism for a WS-Policy expression. 

Target: Section 4.2 of the WS-Policy, Appendix A. 

Proposal: 

Allow xml:id as a permissible mechanism for identifying policy expressions in addition to wsu:Id 

1. Replace 

{/wsp:Policy/@wsu:Id 

The identity of the policy expression as an ID within the enclosing XML document. If omitted, there is no implied value. To refer to this policy expression, a URI-reference MAY be formed using this value per Section 4.2 of WS-Security [WS-Security 2004].}

With 
/wsp:Policy/{@wsu:Id | @xml:id} 

The identity of the policy expression as an ID within the enclosing XML document. If omitted, there is no implied value. To refer to this policy expression, a URI-reference MAY be formed using this value per Section 4.2 of WS-Security [WS-Security 2004] when @wsu:Id is used. 

2. Repeat last example in Section 4.2 using xml:id in addition to wsu:id (last paragraph of Section 4.2) to illustrate the form. This is purely editorial. 

3. Add normative reference to xml:id [XMLID] in A.1.  
Personal Note: 
I have chosen to retain the reference on wsu:Id given the expected schedule of the publication rather than removing it due to existing support on this attribute in the existing implementations. 

We could also add a note in the framework/primer when it is not desirable to use xml:id but rely on wsu:id if the wg feels that is necessary. 

References: 
[XMLID] http://www.w3.org/TR/xml-id/ 
[WS-Policy] http://dev.w3.org/cvsweb/~checkout~/2006/ws/policy/ws-policy-framework.html?content-type=text/html;%20charset=utf-8